Process for making paper pulp



Feb. 23,1926. 1,574,026

F. K. FISH, JR

'- FROCESS FOR MAKING PAPER PULP Original Filed Nov. 5', 1920 INVENTOR.

"ATTORNEY.

Patented Feb. 23, I926.

uurrn srarss PATENT overeat FREDERICK K. FISH, JR, 0F WINDSOR MILLS, CANADA, ASSIGNOR 'IO WOOD TfiIdOZDUCTS & BY PRODUCTS CORPORATION, A CORPORATION 01 NEVADA.

PROCESS FOR- MAKING- PAPER PULP.

Application filed November 5, 1920, Serial No. 421,970. Renewed May 22, W25.

To all i /mm it QN/j/ concern.

Be it known that FREDERICK K. FISH, r., a citizen of the United States, residing at lVindsor Mills, Canada, has invented certain new and useful Improvements in Processes for lvlaking Paper Pulp, of which the following is a specification.

This invention relates to improvements in a. process for manufacturing paper pulp from plant substances.

In my co-pending application for patent Serial Number 275873, filed Feb, 8, 1919, covering a process for a similar invention I soften the material being treated, then remove the soluble constituents and melt the insoluble resins and thereafter subject the material to a digesting action. In these steps the softening of the substance is accomplished by moisture and heat while the solubleconstituents were subsequently re moved by the action of superheated water. ln my former application the volatile and like vapors were wasted, and the treatment unduly prolonged.

I have discovered that the treatment of the plant substance from which the pulp is to he formed, can be augmented to a very considerable degree, and the result obtained more rapidly by initially charging the vapors and the 'water'in which the material is subsequently treated with extractive substances of wood. and While being treated enriching the mixture with like extractive substances taken from the material being acted upon.

Therefore one of the essential features of my present. invention resides in initially charging the vapor and water employed in the treatment, and collecting the resultant liberated extractivesfrom the material under treatment and converting same into a mixture with theextractivcs initially employed to act on the contained constituents of the plant substance under treatment.

My experiments have demonstrated that when the plant substance is subjected to an tll'lnOSPllOl'G of heated vapor charged-with jextractives of the material under treatment after removed by the Water charged with the e extractives. Furthermore, I find that the vapor and water charged with these extractives will render the insoluble constituents remaining in the material under treatment more susceptible to removal by the di esting chemical solution subsequently emp oyed.

In carrying out my invention I aim to utilize u on the material under treatment all the li erated gases and charged vapors from themater-ial under treatment, to superheat these gases and charged v'apoys after their initial use and after such use condense and trap them, using the condensate to strengthen the Water which has also been 'charged with similar extractives, which is si'ibscqnently employed in the proceess thus lending economy and saving timein the manufacture of the pulp.

It is essential in the manufacture of pulp that the fibers of the plant substance be separated one from the other but reserved against mutilation or disintegration. To accomplish this it is highly important that the gums and excess resins be removed to allow the remaining resins to become broken up and to spread throughout the entire mass of the material under treatment and especially into the larger pores of the material under treatment and in consequence be easily and quickly removed by the digesting chemical solution subsequently employed. In my former a plication the gums are removed indepenc ently of the resins and by diflerent liquids. The respective steps in'my resent ap lication are greatly improved iy the ad ition of the mixture of the complex extractives of the material under treatment.

In the manufacture of pulp it is Well recognized that due to the presence of the gummresins and like constituents in wood, peculiar chemical reactions take place while under treatment by the digesting chemical solution and also after the nip has been manufactured into paper and certain acids and insoluble substances are formed thus producing an inferior pulp, and unless these deleterious substances arefremoved from the wood prior to treatment bythe digesting chemical solution a much longer treatment is required and at a higher temperature and pressure which tends to Weaken and sometimes dissolve the cellulose itself. These objectionable features are overcome by the process herein disclosed. In other words in the present application. the plant substance treated to the action of superheated volatile vapor extractive substances fromwood, etc, inthe form of vapor and in the form of liquid for the conversion of the contained complex resinous substances and gums, into a more soluble form with the object of removing from the material under treatment rot only soluble but insoluble materials, prior to the application of the digesting chemical solution.

To illustrate one way of carrying out the invention 1 have diagrammatically illus-- tratcd an apparatus in the accompanying drawing, in which,

1 indicates a chamber, or sweat box pro- 'vided with a door or doors 2, 2 an interior track or similar supporting means, and spray pipe 2". This chamber may he supplied with steam. or heated air through a pipe lmidinp lrom a suitable source, or heat and vapor may be introduced to the chzunber through a pipe 19, leading from a digester hereinafter referred to, and it desired heat may be introduced to the chamber by means of coils 2 Communicating with the top of the chamber 1, is a pipe 1' which leads into an air tight hot box 1", suitably heated by coils. Comnnniicating with the opposite end of the hot box is a pipe 1 which leads into the chamber, a valve or valves 1 being provided to control the pipes. In the pipe 1" is a fan 1, to draw the vapors from the topof the chamber, and pass them through the hot box and through the pipe 1 and into the chamber preferably below the track. The fan creates a suction through the sweat box, and quickly draws off the vapors, and the latter are reheated in the hot box to a tie gree preferably above the boiling point of the adn'nature, but the temperature should not be such as to polymerize the terpenes or destroy the plant substances. The vapors thus reheated are employed to act on the plant substance to assist in melting, dissolving' and removing a portion of the water soluble and Water insoluble constiuents from the Plant. substances. This allows of a more ready and effective removal or not only soluble but also water-insoluble constitucnts ov the charged water subsequently emploved. 'il'he vapors are of course charged with the terpcnes, and terpene alcohols etc, which, when superheated, act to further the extraction of like constituents and a portion ot the resinous substances in the plant sub stances.

"the chamber extends below the sur'tace the ground to form a tank Ill-d con- 7 liquid initially charged with tor-- and other volatile components of which may have been extracted from Wood. sax-dust. or other waste material, and t :mtom of the tank coils 2 to liquid. Communicating with, the

tank below the water level is a pipe 3, extending into the top of the chamber, and connected to the sprays 2* to spray the liquid onto the plant substances. In the pipe. 3 is a pump 5 to force the liquid from the tank 1O1 to the spray pipe. 2. It de sired a branch pipe 6 may join the pipe 3, and by means of suitable valves, cold water may be sprayed on the plant substance at intervals.

From the top or dome of the chamber extends a pipe 5, connected with coil 6 of a condenser 7, the coil extending into a collcctor tank 10.

A vacuum pump 9, connects at its suction end through pipe 11 to a second coil 8 of condenser 7, discharging into collector tank 10. Coil 8 is connected at its upper end to a pipe 8 which leads to a digestcr 13. The condenser 'l' is arranged to be supplied with vany suitable cooling agent, as water or brine, which is circulated from a bottom inlet to an upper outlet, in the usual construc tion.

The collector tank 10 and the liquid tank 101 are practically one, and communicate with each other, as by means of a pipe 7, having a valve 7*.

Located'adjacent to the chamber 1, is a digester 18, arranged to receive the truck or the like. carrying the plant substance, and in the digester there is a track preferably in line with the track 2, in the chamber 1. and between the container and the chamber 1, there will be a track for conveniently transferring a car carryinr a load of plant substance from the chamber 1. This digester is provided with a pertorated coil ll. provided with a valve 143, to supply steam to the interior of the digester. and also steam heating coils 15, having valve. 15. The pipe 8 connecits with the top of the digaster, and in it is a safety-valve 18. which also may act as an ordinary controlling, valve. The pipe ll), leading, from the sweat chamber 1, is connected to a pipe 15)", the ends of which are connected to the top of a tank 20, and the digestcr 13, the pipe 15) having two controlling valves 19 and 19 for a purpose to be explained.

In. the tank 20, are heating coils Q4, having a valve 25, and condensation pipe 26. connected with a steam trap 2}". which preferably discnarges through pipe 28. into tank 10-1, and in this tank there may be perforated steam pipes 20*.

The suction end of a force-pump .29, is connected with the collection tankll'), by pipe 30. and the discharge end of said pump is connected to the tank 2), by a pipe 3 having a valve 32.

A pipe 34. is provided with a valve I33. and communicates with the digestcr l3. and with tank 20, by a branch pipe 36, provided with a valve. 3?, Spray pipes 38, connected ed in the digestcr.

steam coils with a supply of cold water are installed at the top of digester l3, and a pipe 39 provided with a valve 40, connects the d-igester 13. with the collector-tank 10. A branch pipe 34", connects with the pipe 34, and by means of valves 34: live steam may be introduccd into the top of tank 20, or the top of the digcstcr 13.

The foregoing description of the conventionally illustrated apparatus is simply for the purpose of outlining a plant for carryin; out my process for the manufacture of pulp, and I will now describe in detail the various steps and the functions accomplished thereby.

Liquid initially charged with terpenes, oils, and other like extractives of wood substance is introduced into tank 20, through pipe 50 by opening valve 51, and it the plant has been previously used, the contents of tank 10-1, are pumped into tank 20, :nd through the medium of heating coils 2t and 20, the liquid is superheated, or in the other words the temperature of the liquid is raised above its boiliiw point, and the pressure is allowed to rise above atmospheric to prepare said liquid for quickly acting on the plant substance later on'when introduced into digester 13.

A truck containing a load of plant substance is run into the chamber 1, and a suitable medium, such as steam, heated air or any combination of themare introduced through the pipeB, this heat is above the boiling pointvof the liquid in tank l0-1 so that it volatilizes and the vapors from said liquid till the chamber 1. After the first truck load has passed through the chamber, and is under treatment in the digester 13, the vapor from the digester 13, may be utilized also, this vapor being hcavilycharged with the terpenes removed from the plant substance while being treat- Valvcs in the pipes 19 and 19 are regulated to allow the passage of steam as desired from eitheror both the digestcr 13 and'tank 20. into the chamber 1 and if necessaryv the heat in the said chamber may be augmented by heat from the It is desirable that the temperature. in the chamber 1 be raised above the boiling point of the admixed terpenes and water. and that the treatment of the plant substance during this step of the process be for one or two hours. depending upon the character of the plant substance or material being treated. The vapors are circulated by the tan 1 throue'h the hot box 1 where they are reheated to assist in raising the temperature in chamber 1 to a desired degree, but not high'i-nough to polymerize t'ho'tcrpenes in the wood or to have a harmful effect upon the plant substance.

The steam. hot liquid producg-rl by the spray, and terpenes or the like vapors in the chamber 1, when reheated and applied to the plant substance penetrate and soften its entire structure as well as the soluble gums and resins of the chips, the combinabeen softened but not as yet volatized, to

move to a certain extent, to the surface of the chips. This siu-t'acewise movement may be increased by the occasional application to the surface of the chips of cold water thru spray pipe 2 the sudden cooling of the surface of the chips causing a partial condensation of the vapors which results in a movement surfacewise of the interior vapors and oils contained therein, as well as of other constituents.

Liquid from the tank 101", is pumped periodically to thespray pipes, to raise the temperature of the plant substance and assist in extracting the softened constituents of the plant substance from the surface.

The chamber 1, being tightly closed, some slight pressure will be created therein and to limit this pressure to the desired amount, excess vapors pass thru pipe 5, and are condensed in the coil 6, and thereupon pass into tank 1O1 and the condensate may thereafter be pumped into the tank 20, to be used with the liquid in subsequent treatment of the plant substance, or sprayed onto the substance thru spray pipes 2*.

The condensate accumulated in the tank 1()-1 will be pumped from time to time into tank 20 to add to the strength-of the distillation of the resins in the chips under treatment, care being taken to regulate the temperature so that there will he no polymerization of the terpeues. Therefore, the valve 1 is opened and the tan 1' sucks the liberated vapors from the top of the chamher and introducessame into the sealed hot box, where they become reheated, and are subsequently directed thru the pipe 1, and into the chamber 1. The result of this action ti l stituents in the chips.

is to create a. circulation thru the chamber, which causes the vapors charged with terpenes, oils, and other volatile substances ,introduced thru pipe 1 to cooperate with the steam and the vapors liberated from the chips, to co-mingle or mix and act promptly pipe 5, and are condensed in tank 10 for;

reuse in the process.

ll'hile bringing up the temperature of the chips by the introduced heat and vapors, the hot spray pumped from the tank 1O-1* is introduced upon the chips, and afterwards comes into contact with the heating coils, a portion of the spray being vaporized and it then rises and reacts together with the vapor otherwise liberated from the chips and that introduced to the chamber, to dissolve and remove a portion of the water soluble and water insoluble constituents of the chips.

As this step is continued terpenes, oils, and other like substances are liberated from the chips in the form of vapor andtogether with the condensate produced from the introduced vapors, as well as from a portion ot the liquid spray, dilute, and partially remove water insoluble constituents of the chips which are collected in the tank below for reuse in the process.

After the chips have been treated in the i 2. chamber 1, tor a sui'iicient time to raise the temperature to the required degree. and to soften the chips and to dissolve and remove a portion of the different constituents, the supply through pipes 23 and 1 is cut oil, or if the vapors from the container l3 are utilized, valve lit and it) or both. are closed, and the load of chips is trai'isferred to the container 13. and a new load is run into the chamber 1.

hen-the load of chips is removed from the chamber, and is exposed to the air, while in transit to the container, the differences between the internal temperature of the chips and that of the/exterior. causes vaporization of the moisture within the chips and an interior movcment surfacewise. this action preparing the, chips for quicker treatment in the next step in the digester 1:3.

The chips ha vino been introduced into the dio'cstcr, the latter is sealed, and valves 1.6 and ltl are. opened, and the vacuum pump 9 is started to create a vacuum of approxi mately 15 inches in the die'cster. To attain the vacuum quickly cold water is forced through spray pipe 38 and up at the chips.

The vacuum further removes terpenes and vapors from the chips and these in passing I through coil 8, condense and are discharged 'ester 13.

into the collector tank 10, for reuse in the process. The vacuum in the digester lowers the pressure within the chips below atmospheric, causing a cellular expansion, which with the removal of the vapors from the chips tends to allow a more ready penetration of the liquid employed in the next step in the process. This vacuum also removes air from the digster preventing discoloration of the resins. The vacuum is broken by the vapors passing from the chips. a

The condensate from tank 10, is pumped into the tank 20, and mixes with'the liquid therein, and the condensed 'terpc'lties and vapors become mixed with the superheated liquid and add to its solvent power. The valve 23, is opened and the superheated liquid passes from the tank 520, to the d The liquid in the tank 20 initially charged with terpenes, o ls and other like extractives from wood to ac-won the constituents of the chips in the treatment of the latter. The movement of the liquid from the tank 20 to the digester is assisted by introducing steam or other gaseous medium through pipefll. upon the top of the body of liquid in tank-20.

As the superheatct'l liquidycontaining terpe1ies, oils and like extractives from Wood, is introduced into the digest'er, to prevent excess pressure Within the digester, and allow the liquid to flow freely into said digester, valve 19 may be opened and the vapor passed through pipe. 15) into the chamher 1 the charged vapors being employed to in the first treatn'ient of chips. The liquid may also be moved into the digester by means of the pump 70. Afterthe liquid is turned into the digester and the chips be come submerged, valve 19 is closed, and steam is turned into the heating coils 1:), to maintain the liquid at a. temperature above, its normal boiling: point, which creates a pressure in the digester or. in other words. the liquid, is maintained in a superheated condition. Steam may also be admitted throueh perforated pipe l It is desirable to heat the liquid to a temperature of or about 245 l1. and a corresponding pressure of about twelve pounds above atmospheric is preferably n'iaintriined.

The chips are subjected to the liquid tut-at ment for a period of approxinlately one or two hours, dtpcudine entirely upon thcna" ture and thickpess of the chips. The superheated liquid. being at high temperature and pressure. and being charged with tcrpeneS. oils and like extractives from wood, and quickly dissolves and extracts liquid st'jluble gums and similar soluble constituents, and also quickly extracts oils, and terpenef. and like extractives from wood and introduces them to the liquid surrounding tl1e cbips and further melts and spreads and partially removes the true resins wh ch are insoluble all in water. As these terpenes, oils, etc., are extracted, they add to the solvent power of the liquid, and extract materials from out the entire structure of the chips, and the materials acted upon by it are dislodged from their original position in the chips, and

those which are soluble in the liquid are dissolved and, due to the surrounding presall) liberated extractives sure and the a itation and ebullition of the liquid surroun ing'the chips, the materials which have been removed become inter mingled or mixed in the entire body ot the liquid. To maintain a uniform composition of .the liquid an active circulation and agitation of the liquid is secured by the pump '70 drawing from the bottom of digester 13, and discharging into the upper opposite end thereof. The liquid thus becomes further charged with solvent extractives, the nature of which is largely dependent upon the character of the plant substance or chips being treated. vIt has been found, however, that in practicing the process, the liquid need in the treatment contains terpenes, resins, oil and ligneous matter and the like} Furthermore, as long as the high heat is maintained, and the fact that the liquid is confined and agitated, the substances are so thoroughly intermixed in the liquid, as to make it impossible to independently distinguish them.

.VVh-ile the treatment is in process, the

also become intermingled in the liquid. and this liquid,

charged and mixed with these substances penetrates the chips and dissolves a portion of certam resinous substances, which are not of themselves soluble in superheated water.

The hemi celluloses such as xylan, mannani', etc, which are ordinarily insoluble in water pass into colloidal solution, a portion being hydrolyzed. A portion of the lignin passes into solution in this step of the process.

When the chips under treatment have been thus effectively acted upon by the superheated liquid, mixed. with contained entractives from wood, the valves 18 and 1t) and 19 are opened, and the vacuum pump is started to quickly bring the pressure in dige'ster 13 to or about atmospheric. At this time the spray ofwater throughthe spray pipes 38,

upon thesurface of the liquid acts to quickly condense a portion of the vapors, and to reduce the pressure above the water. The pipes 19 and 19 are opened and assist in reducing the pressure within the digester. A portion of the vapor in the digester 13, passes through said pipes 19 and 19 to the tank 20, and to the chamber 1. This sudden release of pressure surrounding the chips causes liquid in the chips to flash into vaporthereby forcing both soluble and insoluble materials in the interior of the chips towards its surface and into the liquid and also causes an expansion of the chips and the individual fibers thereof. This is a very important step in the process. ll'hcn the pressure within the container reaches atmospheric or lowered to any desired degree, the-temperature and pressure of the liquid surrounding the plant substance may again be raised. These sudden changes in pressure and temperature may he resorted to as many times as may be deemed advisable.

After the plant substance has been treated in superheated liquid as above, one or more times, additional liquid from tank 20, is forced over tolill the dgcster 13, by the pump 70, and by continued operation of the pump, pressure of about 15 lbs. is again created in said digester while the chips are still submerged, but the liquid at this time is not superheated. This pressure is suddenly released by passing some of the liquid back to tank 520, this action effects a sudden lowering of the pressure surounding the chips and causes an outflow of theliquid from the interior of the chip.

The valve 23, is again opened and the pump forces the liquid from the digester to tank20 for reuse.

Following this step, valve 18 is opened, and the vacuum pump 5) is started, and a vacuum is again created in the dig-ester 13 to remove from the chips liquid which has been forced into it, and simultaneously cold water is sprayed onto the chips through the spray pipe 38. to condense quickly the vapors and assist in creating a vacuum quickly.

The liquid treatment maybe repeated and alternated w th u vacuum, to insure of the extraction oi the elements from the chips,

as it has been found that the plant structure ouently employed. complex make up ot' the plant substance ccrftain of the insoluble constituents are ordinarily not subject to removal by heat and inc; soluble and insoluble onstituents including a portion oi the li 'nin from the material under treatment prior to the treatment by the digesting chemical solution. That .is to say up'to the time of the chemical digesting step ater soluble constituents and insoluble constituents of the material under treatment had been removed and constituents which it may be desired to remove had been melted and spread throughout the structure of the substance so as to make such constituents more susceptible to the action of the acid or like digestive solution subselt is true that in the boiling water. However i: have found that by the employment of the superheated water, charged with wood extractivcs and the incident pressure upon material which has been previously acted upon by such charged vapors much of the insoluble constituents is rendered subject to attack and a very considerable portion thereof removed. This lends great we ght to the value of the process when the chemical digesting period is reached. Hence it is necessary to employ the chemical digesting solution but for a short space of time to complete the digestinc; action. The chemical digesting solution may be reused as the previous digestion by the charged water has 'aused a removal of soluble and insoluble constituents from the wood which under other process neutralizes the chemical solution.

As the effects of the chemical digesting- Solution are well known it is not necessary to describe its action in detail su'liicicnt to say there is a quick and effective removal of the reniaininc resins. lie nin and like corn stituents of the wood in coi'iscquence ot the previous removal of soluble and insoluble constituents by n'cvious steps of my 'n'occ,-:s and under a much lower pressure and teinperature, the fibers are separated and the woody structure is in no wise marred or destroycd, which results in a pulp 'l'rcc oi substances and elements which in other processes atiect the paper subsequently 'n'oduceih After the digesting chemical action is completed the digesting, chemical solution is drawn oil. the dig'cstcr is tilled with water preferably heated and pressure created in the digester'to cause-the water to penct ate the individual fibers and remove quickly and ell'ectively any of the chemicals from the chemical digesting solution which may have remained in the pulp and which, it left therein, would act as an antic-blur.

In the chemical digesting step as now practiced in the manufacture of pulp, the chemicals employed become intermixed with the constituents of the Wood and preclude the future use-of the chemical, and as a; rule soluble such chemical is run off as waste, and in time the surrounding streams and rivers become contaminated or :olutcd, a condition which is dangerous to life and health. According to any invention, only a portion of the lingnin, resins and like constituents are the only elements attacked by the chemical digesting solution with the result that it may be constantly reused.

1n the reuse of the charged water in which the plant substance partially digested all the oils, terpenes, gums and other-extractives, and in time the water becomes so mintaniiinated that it must be replenished. However before. thisstage is reached, I take advantage of the extractive mixture and employ it in future operations. These complex cxtractivcs when mixed with heated water and the attendant high temperature and incident. pressure will effectively dissolve and remove like substances. and it is for this purpose that I reuse it in the present process. It enables me to complete the digestion in a remarlmbly short space of time, it is ccoi'ioinicai and it iscllec ive.

The term vacuum as herein used is irtendcd to mean a reduction of pressure to such a deq'rcce. below the higher pressure employed as to cause a substantial expansion of residual air or vapor in the interim ot' the wood which elt'ecis an opening up of the interior fibrous structure. i

llhcabove description defines a process involving several ii'idcpendent steps, each of which {tends in its sequence and relation to the other steps to produce. a probably better result the linal Pl'Otlllti'. than if such par ticular step were entitled. However. it is to be understood that certain of said steps may be replaced by others ot a similar or even p 'iviously known type without affect ing; the result. except in matter of degree, with the exception however. that the important and essential step of the process is requircd in every in tancc to produce the. result soughtv This essential and important step of the process consists in subinercino the plant. substance in superheated liquid charged with volatile solvent ottractivcs ol the substance to thereby melt. dissolve. and remove, desirable}iortions oil the soluble and water-insoluble cinistitucins oi the substance and then rci'novine the liquid with its con taiucd ext'ractivcs trom about the plant snbstance, and thereafter digesting the plant substance in a separate chemical solution. Thisimportant step is also subject to specific moditication in its utilization to extract the. and. watei insolublc constituents from the plant substance. for example, in alternately increasing and dccleasing the pressure and tem ierature ol the liquid in which the plant substance is submerged, to

cause such variation in pressure to alter-. nateiy force the liquid charged with the llt) llS

' being treated; utilizing this liquid after its,

volatile extractives into the plant substance and withdraw it therefrom With the contained extractives, and the further use of this charged liquid for the further treatment of the same or seubsequent mass of plant substance. This liquid charged with the volatile extractives of the plant substance is maintained in such charged condition for reuse, to thereby take advantage of the solvent effect of these volatile extractives in the treatment of fresh material.

Therefore, it is to be understood that while the steps of initially treating thevplant substance to a heated moist fluid \vhiclr co ntains volatile extractives of the"snbstiuice initial effect on the substance as a circulat-EK inp; medium through and around the plant substance, tend to a more effective and quicker action of the process as a Whole when used prior to the essential step of the process, such steps are not absolutely essential to the process herein described and need not necessarily be used to secure a desirable result from the use of the essential step above described. Therefore, such additional steps will be hereinafter claimed merely as steps in a process for the making of paper pulp from plant substance, as they have their independent advantage in rendering the result ofi the essential step quicker in point of timejand more perfect in quality of product.

l. The proc'essxof making paper pulp from plant substances, consisting in subjecting the plant substance to a heated medium containing added volatile extractives from the plant substance, then submerging the plant substance in superheated liquid charged with volatile extractives of the plant substance.'tlien removing the liquid from around the plant substance, and thereafter further digesting the plant substance in a separate chemical solution.

9,. The process of making paper pulp from plant substances, consisting in subjecting the plantsubstance to a' heated, moist medium charged with volatile extractives from the substance, then submerging the plant substance in superheated liquid charged with volatile solvent extr'actives of the substance, then removing thecharged liquid from around the plant substance, and

thereafter digesting the plant substance in a separate chemical solution.

' The process of making paper pulp from plant substances, consisting in subjecting the plant substance to a circulating moist medium charged with volatile ex tractives from the substance, then submerging the plant substance in superheated liquid under pressure charged with volatile solvent extractives of the substance, then' Withdrawing the liquid from around the plant substance, and thereafter further digesting the plant substance in a separate chemical solution.

l. The process of making paper pulp from plant substance, consisting in subjecting the plant substance While in a scale: chamber to the action of a heated medium charged with volatile extractives of the plant substance, then submcrging the plant substance in superheated liquid charged with volatile extractives of the substance, then Withdrau'ing'the liquid from around the plant substance, and thereafter further digesting the plant substance in a separate chemical solution.

5. The process of making pulp from plant substance, consisting in treating the substance with superheated \vater initially charged with volatile extractives from wood and thereafter in use, also charged with volatile extractives of the plant substance of the character being treated, to thereby dissolve, melt, and decompose constituents of the substance, said liquid being at a temperature above the boiling point of water and at a pressure greater than atmosphere, withdrawing the liquid from around the substance, and thereafter further digesting the plant substance in a separate chemical solution.

6. Those steps in the process of making paper pulp from plant substance, consisting in submerging the plant substance in heated liquid initially charged with volatile solvent extractives of the substance, subjecting the mass to alternate increases and reductions in pressure, withdrawing the charged liquid from the plant substance and thereafter digesting the plant substance in a separate chemical solution.

7. Those steps in the process of making paper pulp from plant substance, consisting in subjecting the plantsubstance to a heated liquid under pressure and initially charged with volatile solvent extractives of the sub stance, suddenly reducing the pressure dur ing treatment to permit extractivcs within the cells of the plant substance to move toward and into the liquid. then removing the liquid from around the plant substance, and thereafter digesting the plant substance in a separate chemical-solution.

8. The process of making paper pulp from plant substance, comprising subjecting the plant substance to heated moist atmosphere charged with the volatile solvent extractives from the plant substance being treated, collecting the charged vapors and condensing same to be subsequently vaporized to act on the plant substance, transferring the plant substance to a digester and submerging the plant substance in superheated liquid initially charged with volatile solvent extractives from plant Substances to melt. dissolve, and remove, a portion of the sol- Ill ' heated nble and insoluble constituents. relieving the pressure from the digester find collecting the vapor from the liquid and collecting same for enriching the liquid in which plant substance is to be treated to form pulp, ren'ioving the liquid, and thereafter further digesting the plant substance in a chemical digesting solution.v

9. The process ofmaking paper pulp from plant substance, comprising subjecting the plant substance to' superheated vapor charged with the volatile solvent extractlves of plant substance together with a supply of air, thereafter submerging the plant substance in superheated liquid charged with the volatile solvent extraetivcs of plant substance to cause a portion of the soluble and insoluble constituents to move s tacowise, ren'ioving the liquid, and thereafter further digesting the plant substance in a chemical digesting solution.

it). That step in the process of making paper pulp from plant substance, which cousis s in subjecting the plantsubstance to a medium initiallycharged with volatile'solvent extraetivcs of the plant substance to ihcreb melt, dissolve, and remove, a per- 't ouv ot' the soluble and water-insoluble cous ituents ot' the plant substance, and circulatingrthis medium through and around the plant. substance in its continually and increasingly enriched condition result-ant from the extractives removed from the substance.

.1 The process of making paper pulp from plant substance, consisting in treating the plant substance in a medium charged with s-xtractivcs ot' the subtsance to dissolve and icmove the water soluble constituents and at the same time mclt certain of the constituents which are not soluble in water, then treating the plantsubstance in superheated water containing extractives of the substance to further, melt and spread the j resins and like. constituents of the plant "substance, and then treating the plantsubstance in a separate digesting chemical solution to remove the resins and like corn stituents to form, pulp.

Those steps in the process of making superheated paper pulp from plant substance, consisting in submerging the plant substance in superheated liquid charged with volatile solvent extractives of the substance, withdrawing the charged liquid from around the plant substance, subjecting the substance to a Vacuun'i to remove material from the sub stance, and thereafter digesting the plant substance in a separate chemical solution.

13. Those steps in the process of making paper pulp from plant substamrc, consisting in subjecting thefsubstancc to a vacuum, then subn'ierging the plant substance in super-- hcated liquid charged with volatile solvent extractives ot' the substance, witlnlrawingr the charged liquid from around the plant substance, and thcrca lter digesting the plant substance in a separate chemical solution.

H. Those steps in the process of making paper pulp from plant. substance, consisting in sulnnergin the plant substance in uid charged with volatile solvent c:\'tracti\'es of the substance, circulatine' the liquid during treatment to maintain a unil'orm composition of such licp uid, uitlulra'u'in r the clutrged liquid from around the plant substance, and thereafter digesting; the plant substance in ascparatc chcmical solution.

15. The process of making pulp from plant substance, consisting; in treating the substance with superheated water initiall charged with volatile cxtractivcs from wood and thereafter in usc. also charged with volatile extractivcs ol' the plant substance of the character beine treated. to thereby dissolve, melt, and decompose constituents of the substance, said liquid being at a tem perature above the boiling: point of water and at a pressure greater than atmosphere,

suddenly reducingthe pressure andtempcrature of the liquidto .turthcr remove by force said melted, dissolved and tlucolllposccl constituents from the substance being trculed, withdrawing;- the liquid from around the substance, and thereafter further digesting the plant substance in a separate chemical solution.

In testimony whercot' l allix'mwsic'nature.

FREDERICK K. FISH, Jn.

lit) 

